Detailed Explanation of Clinical Diagnosis and Prevention Methods for Mycoplasmal Pneumonia of Swine (Swine Enzootic Pneumonia)
Detailed Explanation: Clinical Diagnosis and Prevention of Mycoplasmal Pneumonia of Swine (Swine Enzootic Pneumonia)
I. Epidemiological Characteristics
Swine enzootic pneumonia is most likely to occur in young pigs and suckling piglets, while adult pigs, lactating sows and pregnant replacement gilts more often show latent infection. In old epidemic areas, the mortality rate is relatively low, because in old epidemic areas the symptoms of pigs are not obvious and the disease follows a chronic course. In new epidemic areas, both the transmission rate and mortality rate of this disease are relatively high, and it more often spreads in an outbreak pattern. Healthy pigs become infected through the respiratory tract when they come into contact with feed or equipment contaminated with the pathogen.
II. Clinical Symptoms
Swine enzootic pneumonia initially manifests mainly as a single cough, with no relatively obvious changes in appetite or spirit. When piglets are affected, it leads to stunted growth and poor development. As the disease further progresses, affected pigs show listlessness and aggravated coughing; in terms of coughing especially, it changes from a shallow cough to a deep cough, and from a dry cough to a wet cough. The affected pigs' breathing becomes extremely difficult, and the respiratory rate increases. In the late stage of disease progression, it turns into open-mouth breathing, poor appetite or refusal to eat. In subsequent development, body temperature gradually rises, and the pigs may even die from exhaustion and suffocation.
III. Pathological Changes
Necropsy of dead pigs shows both edema and emphysema in the lungs, and "shrimp-meat-like" lesions appear in the cardiac lobe, intermediate lobe, apical lobe and the anterior margin of the diaphragmatic lobe of the lungs. As the disease continues to worsen, the lung lobes of pigs show different conditions, among which the boundary between normal lung tissue and the consolidated area is very clear. Therefore, when diagnosing this disease, relevant personnel need to pay attention to mixed infections caused by swine lungworm disease, swine pasteurellosis and swine influenza.
IV. Diagnosis
(1) A preliminary diagnosis can be made based on epidemiological characteristics, clinical symptoms and necropsy lesions; confirmation requires serological diagnosis or X-ray diagnosis.
(2) Differential diagnosis:
① Swine influenza is an outbreak disease with a relatively fast transmission speed, and the body temperature of affected pigs rises markedly. Swine enzootic pneumonia has a relatively long epidemic period, and its transmission speed is slower than that of swine influenza, and the body temperature of affected pigs does not rise markedly.
② Acute cases of swine pasteurellosis mainly manifest as fibrinous pleurisy and septicemia, and the changes of fibrinous pleurisy and septicemia can be clearly observed on necropsy; in chronic affected pigs, necrotic foci or purulent foci in the hepatized area can be seen on necropsy. However, pigs with swine enzootic pneumonia show no major changes in appetite or body temperature, and also no changes of pleurisy or septicemia; only meat-like changes appear in their lungs.
V.TreatmentRegimen
Use 0.25% procaine to dilute 30-40 mg/(kg·bw) oxytetracycline hydrochloride, and administer by divided-site intramuscular injection, once a day, for 3-4 consecutive days.
VI. Preventive Measures
(1) Regularly ventilate the pig house according to changes in climate and season, which can effectively reduce ammonia concentration and ensure fresh air in the pig house, thereby avoiding infection through the respiratory tract. Ensure balanced and rational nutrition for pigs; in addition, the temperature of the pig house also needs to be controlled, and through warmth preservation and cold protection work, ensure the temperature difference between morning and evening stays within a moderate range. During the breeding process, it is also necessary to reduce the number of times of mixing groups and transferring pens; by creating a clean, comfortable and warm environment, the probability of occurrence of swine enzootic pneumonia can be reduced.
(2) Adhere to the system of self-breeding and self-raising and all-in-all-out, strengthen sanitation and disinfection work in the pig house, and at the same time add tiamulin to the drinking water for the pig herd to drink continuously for 7-10 days, which can effectively prevent the occurrence of this disease.
(3) Vaccinate in a timely manner.